Web tension control



May 1, 1956 Filed Feb. 9, 1953 FORCE. CHARACTERISTIC OF SPRING 90 m vTO E BUTTON 51-0? cmcun' TORQUE IN.- L55.

2 Sheets-Sheet l TORQUE EXERTED BY SPRING 42 OPERATING BAND (urr FORCE TO B OVERCOML BYSLOATING ROLLER 5 mavncmmr or PLUNGI-R or VARIABLE pnsaaun: REGULATOR 4O TORQUE EXERTED BY COMFENSATING CYL- 8O RANGE OFMWEMENT OF FLOKTNG ROLLER Dl 7 4" MOVEMENT OF FLOATING ROLLER INCHES aaL 1 Henn LL qncQohorifi r' CATTORNEZY/ May 1, 1956 H. L. MOWHORTER 2,743,881

WEB TENSION CONTROL Filed Feb. 9, 1953 2 Sheets-Sheet 2 45 IWLMQ United States Patent WEB TENSION CONTROL Henry L. McWhorter, Hinsdale, Ill., assignor to The Goss Printing Press Company, Chicago, 111., a corporation of Illinois Application February 9, 1953', Serial No. 335,762

22 Claims. (Cl. 242-75) The present invention relates to web tension control systems of the type finding particular utility in web-fed printing presses.

Web breakage, which is both costly and hazardous in a high speed printing press, has been blamed almost universally on defects in the web. It has been my observation, however, that web breakage is traceable in most instances to the inability of conventional tension control arrangements to handle transient disturbances caused, for example, by rolls which are out-of-round because of mishandling during shipment or the like. To improve the situation, steps have been taken to increase the sensitivity of the conventional systems. Simply increasing sensitivity usually causes a tendency to overcontrol, making it necessary to resort to excessive use of shock absorbers, thereby sacrificing speed of response. More elaborate systems have been suggested employing derivative action; however, such systems are not only expensive but require more frequent adjustment and maintenance.

It is an object of the present invention to provide a tension control system which is simple and inexpensive, but which nevertheless enables control of tension under all conditions encountered in the operation of modern presses, substantially reducing web breakage. It is another object to provide a tension control system which is capable of overcoming transient disturbances and particularly those disturbances caused by out-of-round paper rolls. It is another object of the invention to provide a tension control system which is capable of correcting disturbances having a wide range of frequency and which is fully effective for both large and small diameter paper rolls.

It is another object to provide a web tension control which avoids any transient loss of tension during slowdown and which prevents momentary overrun of the roll when the press motor controller is moved in the decrease speed direction.

It is an object of the invention to provide a control arrangement which overcomes the problem of belt slap.

It is a further object of the invention to provide a'tension control system which is easily set or adjusted by the press operator directly in terms of web tension.

It is still another object of the invention to provide a control system which is sensitive and which requires only a small amount of energy to produce a corrective change.

It is an object to provide a control system which eliminates waste of pressure fluid and which has extremely low power requirements under normal running conditions.

Other objects and advantages will be apparent upon reading the attached detailed description and upon reference to the drawings, in which Figure 1 is a schematicdiagr'am of the present control system as applied to a conventional printing press.

Fig. 2 is an external view of the major control components used in the system of Fig. 1.

Fig. 3 shows a cross section of the variable pressure regulator employed in practicing the present invention.

Fig. 4 shows the net force characteristic of the variable pressure regulator.

Fig. 5 shows the force characteristic of the deceleration spring.

Fig. 6 shows the means for'energizing the deceleration solenoid.

Fig. 7 shows diagrammatically the position of the emergency valve when making a red button stop.

While the invention will be described herein in connection with a preferred embodiment, it will be understood that I do not intend to limit the invention thereto, but intend to cover all alternative constructions and uses falling within the spirit and scope of the appended claims.

Turning now to Figs. 1 and 2, a control system constructed in accordance with the present invention is shown installed on a conventional printing press. The printing press is indicated at 10, and has the usual arrangement of printing and impression cylinders. A web 11 is fed from a roll 12, which is mounted on a spider 13 in a web supply mechanism 14 located below the press floor. For the sake of simplicity conventional mechanisms for bringing the roll up to speed and for effecting a splice or paster have been omitted from the drawing. The web, after leaving the roll 12, passes over a conventional cocking roller 15 having an adjustment 16.

- In order to produce tension in the web 11, a brake is provided having a belt 20 and brake cylinder or actuator 21. Only one belt and one brake cylinder have been shown. It will be understood that in a normal installation a plurality of belts are used, each connected to a brake cylinder, the cylinders being connected in parallel to the source of pressure fluid.

' In practicing the present invention, improved means are provided for detecting a departure in the desired value of web tension and for causing pressure fluid to be supplied to the brake cylinder in accordance with such departure to eifect a corrective change in braking force. The control mechanism for accomplishing this is indicated generally at 25, the physical appearance being set forth in some detail in Fig. 2. To simplify understanding, primary reference may be made to Fig. 1, which is a schematic representation of the various parts used in the system. Air is supplied from a compressed air source through a line 30. The pressure is adjusted by means of a constant pressure regulator 31 having an adjustment 32 and an indicator dial 33. Such regulator is of conventional design, holding the set pressure in spite of variations in the supply line.

The function of the regulator 31 under emergency or red button stop conditions will be discussed at a later point. From the regulator the air is fed into a line 34 and is stored in a reservoir 35.

In order to control the pressure of the air flowing to the brake cylinder 21 under normal operating conditions, a variable pressure regulator 40 is used having a control rod 41. The regulator is of the type having an internal control spring 42 and is so constructed that the pressure appearing at an output line 43 is determined by the position of the control rod 41 and the degree of compression of the spring 4-2 associated therewith. I

Arranged in the path of movement of the regulator control rod is a floating roller 50 which engages a loop of web indicated at 51. The floating roller 50 is mounted for movement in a direction to lengthen and shorten the loop of web. In carrying out the invention the floating roller is suspended by a pair of pendulum-like arms 52 having upper pivots 53 and roller bearings 59a. An arm is located at each end of the roller but only one of them is shown in the drawings. The Web subsequently passes over an output roller 54 and into the press. 7

For the purpose of setting the amount of pressure to be exerted by the brake cylinder 21 and therefore the average web tension, the floating roller 50 is equipped with a loading cylinder 55 having a plunger 56 arranged generally opposite the plunger 41 of the regulator. The pressure in the loading cylinder is adjusted so that a predetermined amount of web tension will keep the floating roller centered in a position of equilibrium. In the present instance the control pressure for the loading cylinder is obtained from an adjustable pressure regulator 60 fed from the supply line 34 and having an output line 63. The pressure regulator may be of the same type as that (31) previously referred to, having a manual control 61 and indicator 62. The regulator is preferably placed at a convenient position on the press and the indicator 62 is calibrated directly in terms of web tension.

In accordance with one of the features of the invention, the loading cylinder 55 is pressurized, not directly by the air in the line 63, but through a liquid medium, preferably oil, the flow of which is restricted in both directions. Turning to Fig. 1, the air-oil interface is established in a reservoir 64 which is connected to the loading cylinder by an oil line 65. Included in the oil line is an orifice or constriction 66. This orifice is so constructed that the movement of the floating roller 50 takes place at a controlled rate. In the present device, which is merely exemplary, a loading cylinder is used having a diameter of three inches and the orifice, using #30 SAE oil, is inch in diameter and one inch in length.

In order to understand the operation of the variable pressure regulator 40, reference is made to Fig. 3. Here it will be noted that the control rod 41 is mounted for telescoping movement within the regulator body and presses against the control spring 42. This control spring in turn bears upon a diaphragm 70 which defines a pressure chamber 71. When the pressure in the chamber 71 counterbalances the force exerted by the spring 42, equilibrium is achieved. The pressure chamber 71 is normally connected to the output line 43 except when a red button stop is made. Such connection is accomplished by an emergency valve 67 which is connected to the regulator by lines 68, 69. The valve has a normal port 67a and an emergency port 6712, the ports being selectively moved into active position. It will be seen in Fig. 1 that the lines 68, 69 are simply interconnected by the valve port 67a during normal running conditions.

For the purpose of bleeding air from the chamber 71 and the output line 43 when the pressure is above the set value, a valve 72 is provided having a poppet 73 and a seat member 74 which is movable with the diaphragm. The seat member 74 is hollow, being vented to the atmosphere through vents 74a. It will be apparent that movement of the diaphragm to the left when the pressure is above the set value will cause the valve 72 to open, thereby permitting passage of air between the seat and the poppet which is exhausted through the vents 74a. This passage takes place until the pressure in the output line 43 and chamber 71 drops to its equilibrium value, at which time the diaphragm is restored to its equilibrium position, cutting of]? further flow.

For the purpose of admitting additional air to the line 43 when the pressure therein is below the set value, a second valve 75 is provided having a poppet 76 and a seat 77, the poppet 75 being mechanically connected to the poppet 73. In operation a drop of pressure in the chamber 71 below the set value causes movement of the diaphragm to the right against the force of the poppet spring 83, opening the poppet 76. Chis causes replenishment of air in the output line 43 until the equilibrium pressure is reached, at which time the poppet 76 closes, cutting off further flow. The two poppets 73, 76 are spaced so as to operate in sequence, the sequential spacing being exaggerated in the drawing for ease in understanding. This insures that the exhaust poppet 73 is completely closed when the supply poppet 75 is open. Stated in other words, the two poppets open alternatively depending upon whether the pressure is slightly below or slightly above the equilibrium value. As a result the pressure in the output line 43 tends to remain at the set value which is determined by the degree of compression of the control spring 42 and, consequently, by the position of the control rod.

To eliminate valve area error an auxiliary piston 78 is provided which is connected to the poppet 76 by a rod 79. The area of the auxiliary piston is so adjusted that the pressure applied to the poppet 76 by the air in the line 34 is almost exactly compensated.

In accordance with the present invention, means are provided for neutralizing the force of the control spring 42 to reduce almost to zero the amount of energy required to operate the regulator. As shown in Figs. 1 and 2, this neutralization is accomplished by providing a compensating cylinder 80 which is arranged at the opposite side of the arm 52. The compensating cylinder has a plunger 81 and is supplied with air through a line 82 which is connected to the regulated output line 43. The area of the piston in this cylinder and the moment arm of the plunger 81 are adjusted so that the torque exerted by the cylinder 80 exactly neutralizes the torque of the control spring 42. For convenience in adjusting the moment arm of the cylinder 80, the latter is provided with an adjusting screw 84 (Fig. 2).

It may be shown that the forces of the control spring 42 and the compensating cylinder 80, once they have been balanced at a particular pressure in the output line (43), remain in balance for all other pressures in the operating range. Suppose, for example, that starting from a condition of balance or equilibrium there is a decrease of web tension below the set value. The resulting unbalance causes the floating roller to tend to move to the right. This produces corresponding movement of the control rod 41. Such movement causes the pressure at the output of the regulator 40 to be increased. The increased pressure is applied to the compensating cylinder via line 82 and the compensating cylinder therefore assists the control rod in its further movement against the force of the control spring until the resulting increase in the output pressure causes a corresponding increase in web tension, thereby arresting and reversing the movement of the floating roller. During the reverse movement the converse takes place. In either event, the forces which must be overcome by the floating roller are reduced almost to zero.

In order to visualize the Way in which the force of the compensating cylinder offsets the force of the control spring, reference is made to Fig. 4. Here the torque 83 exerted by the compensating cylinder is shown equal and opposite to the torque 84 exerted by the control spring. In the device shown in the drawings the force required to operate the regulator is approximately 300 pounds at a representative point in its range when the compensating cylinder 80 is not used. With the compensating cylinder, the force is reduced to about 4 pounds, which is the amount of force required simply to overcome friction and may be indicated by an operating band over the range of plunger movement. This force corresponds to a web tension of two pounds since the web is doubled back upon itself. A change of two pounds in web tension is accordingly required to initiate a corrective change in tension. This is desirable since it insures that the device will not operate with only negligible changes in tension, and, in any event, the two-pound force distributed over the entire width of the web is sufficiently small so that the sensitivity of the tystem is not adversely afiected.

In accordance with one of the features of the invention, the regulator and associated parts are so constructed and arranged that an extremely small movement of the floating roller, on the order of A; to 4 inch, is effective to increase the braking force from near zero to a safe maximum value, and stops are provided to limit the roller movement to such range. The stops in the present instance are located on opposite sides of the depending arm 52 and have been designated 85, 86. A safe maximum value of tension is that which will, under all normal conditions of operation, produce a web tension which lies somewhat below the winding tension employed in the mill where the paper was made. In the case of ordinary newsprint, the safe maximum value is about 5 lbs. per inch of web width.

Devices constructed in accordance with the above have shown a number of surprising advantages considering the simplicity of the arrangement. The system is extremely sensitive but Without any tendency to overcontrol. The system is capable of correcting both long-time disturbances, for example, those resulting from changing roll diameter, as well as extremely short transients caused by an out-of-round roll of paper rotating at maximum press speed. The arrangement is particularly satisfactory for taking care of the transient disturbances resulting from the making of a paster and the percentage of successful pasters is much higher than with conventional tension control arrangements.

The reasons for the improved performance are not completely understood. One of the reasons is believed to be the two-way shock-absorbing action 'which has been incorporated into the loading cylinder, the shock-absorbing effect being provided by the orifice 66. Since the orifice affects the flow of pressure fluid equally in both directions, there is no ratcheting or excessive buildup of force as a result of rapidly repeated transient effects such as those caused by a roll which is out-of-round. A related feature which is of great practical advantage is the limitation of movement of the floating roller to approximately one-quarter inch. This has been found to increase the rapidity of response and inherently limits the amount of momentum which can be built up in the bodily movement of the floating roller and its associated arms. I have found it of advantage to reduce the inertia of the floating roller and its associated arms to the lowest practical point, keeping in mind the necessity for characteristics.

It can be shown that the present device corrects any tendency toward changes in web tension in two ways, depending upon whether the changes are of a gradual or transient nature. In the case of those changes which fall outside of the transient category, movement of the floating roller causes a resetting of the control element 41 on the variable pressure regulator, thereby causing a corrective change in the braking force applied by the cylinder 21 as previously noted. Transient changes, caused, for example, by an out-of-round roll, are not corrected in this manner because of the inertia of the roll and since it is not possible for the control system as a whole to operate at such a high cyclic rate. Instead, transient changes are absorbed by the movement of the floating roller 50. Thus, upon a transient increase in tension due, for example, to the unrolling of the web from the low spot on the roll, the floating roller 50 is drawn to the left, shortening the loop. In moving toward the leftthe floating roller moves the piston in the cylinder 55 and the resultant flow of oil through the orifice 66 provides a shock-absorbing efiect. Similarly, upon a decrease in tension due to unrolling the web from the high side of the roll, the Web tension drops below the equilibrium value and opposite movement of the piston in the loading cylinder 55 occurs. The rapidity of movement is again dependent upon the flow of oil through the orifice 66, the shock-absorbing action being the same in both directions. For a given travel of the floating rollerthe shock-absorbrange of movement is small.

6 large so that the reactive force is below that which will cause breakage of the web when taking web from an out-of-round roll of small diameter.

While I prefer to limit the movement of the floating roller to about one-quarter inch, it will be understood that the range of movement may be somewhat greater or somewhat less than one-quarter inch without departing from the invention, and may range from approximately 5 to approximately 1 inch. I have found that when the movement is limited to less than about A inch, there is risk of hunting. Such hunting may take place at a rate of about cycles per second, being dependent upon the inertia of the paper roll and the resiliency of the web. This tendency toward hunting is believed due to the resilient forces built up in shock absorbers when the Above a range of movement of about one inch, it is believed that a difierent set of factors comes into play. Observations show that the shock-absorbing action, i. e., the resisting force, must be increased when the range of movement of the floating roller is increased in order to absorber may become excessive.

ing action, i. e., the diameter of the orifice 66, is made sufliciently small as to prevent hunting, yet sutficiently range of the floating roller is about an inch. However,-

where the range is substantially greater than one inch the correspondingly increased reactive force of the shock It is believed that this is one of the factors which has caused a high percentage of web breakage in the past.

Further in accordance with the present invention, I prefer to connect the brake cylinder 21 to the high tension side 20a of the brake band 20, the low tension side 2011 being simply anchored as shown. I prefer also to couple a cushioning spring 87-to the high tension end of the belt. For reasons not yet completely understood, it is found that this arrangement reduces the amount of belt slap and enables a smoother control when used in combination with the control system described above. In the present device we have found that the constant of the spring 87 should be approximately 25 to 35 pounds per inch extension when used with a Phosphor-bronze belt four inches in width and when employing a brake cylinder having a normal range of up to 200 pounds of force on the loop of the belt-pulling cable.

In accordance with one of the more detailed aspects of the invention, means are provided for increasing the speed of movement of the floating roller in the loopelongating direction as an incident to reduction in press speed. More specifically, means are provided for resiliently moving the roller to its right-hand or increase tension position independently of the loading cylinder 55 and its associated shock-absorber. This is accomplished in the present instance by a spring 90 which is connected to the armature of a solenoid 91. The solenoid is operated automatically as an incident to slowing down the press, for example, by the arrangement shown in Fig. 6. In this figure the controller for the press driving motor is indicated at 92. The controller is provided with a rack and pinion 93, the rack being connected to a dashpot 94 having a plunger 95 provided with a small orifice. Coupled to the dash-pot are contacts 96, which are normally held in open position by a spring 97. It will be apparent to one skilled in the art that movement of the controller 92 in the decrease speed direction causes closure of the contacts 96, the contacts 96 being opened by the spring 97 as soon as controller movement ceases.

Closure of the contacts 96 causes bottoming of the solenoid 91, which moves the spring 90 into its operating 7 position. In practicing the invention, the spring 90 preferably has a high rate on the orderof 66 pounds per inch, and the spring is arranged so that it is active only over the left-hand or light braking force portion of the range of roller movement.

For ease in understanding the operation of the spring 90, the characteristic of a typical spring is set forth in Fig. 5. In this figure it is assumed that the solenoid is bottomed and that the spring is in its active position. Under such conditions the spring is capable of applying full pressure to the arm 52 of the floating roller when the latter is at its left-hand limit of movement (as limited by the stop 85), and capable of exerting a decreasing force as the floating roller moves to the right. To review the operation, it will be assumed that the controller 92 is moved in the decrease speed direction at a time when the floating roller 50 is in the left-hand portion of its range. The resulting closure of the contacts 96 causes the solenoid 91 to be operated, thereby bringing the spring 90 immediately into engagement with the arm of the floating roller, moving the latter over into its right-hand position. This causes an immediate increase in pressure of the output line 43 of the regulator, causing the belt 20 to be tensioned, thereby forestalling any tendency of the roller 12 to over-travel and causing the kinetic energy of the roller to be quickly absorbed.

During the above sequence, the arm 52 of the floating roller is moved to the right independently of the loading cylinder 55, and the arm 52 may actually move out of contact with the cylinder plunger 56, due to the fact that the movement of the plunger 56 is retarded by the shock-absorbing effect of the orifice 66. As a result, the system includes the advantages of the shock-absorbing action without the usual disadvantages, the shock-absorbing effect being superseded upon a reduction in press speed. It is to be noted that the action of spring 90 does not interfere with normal tension control by the floating roller. Thus, as soon as the spring 90 has moved the floating roller into the right-hand portion of its range, which occurs very quickly, on the order of a fraction of a second, the floating roller continues in complete control of the tension. The function of the spring 90 is to move the floating roller over without delay to the position which it must occupy in order to produce the increase in braking force which is required by the slowdown of the press. When the controller 92 reaches its new position, the contacts 96 are opened, thereby deenergizing the solenoid 91, retracting the spring 90 out of its active position.

In describing the operation of the spring 90 it has been assumed that the floating roller is in the left-hand portion of its range of movement at the time that the speed controller is moved in the decrease speed direction. This is a rather extreme case and under more average conditions it is likely that the floating roller will be in the center portion of its range of movement at the time that a reduction in press speed is initiated. The only difference is that under the latter condition the force applied by the spring 90 to the floating roller is proportionately reduced. Should the floating roller already be in the right portion of its range at the moment that a decrease in speed is initiated, the spring 91) will have substantially no effect. In short, the amount of force exerted upon the floating roller by the spring 90 is tailored automatically to the job which must be done.

The above control system is particularly well adapted for making a red button stop under emergency conditions. For this purpose, an emergency solenoid 98 is provided for operating the emergency valve 67. The solenoid is under the control of the red button 99. It will be understood that the red button 99 is a part of the control system normally associated with a printing press, and may be any switch used for shutting down the press under emergency conditions whether operated manually or automatically as by a web brake detector.

When the red button is operated, the valve 67 is switched to its alternate condition set forth in Fig. 7 in which the valve port 67b connects the line 68 (from the regulator 40) to exhaust, and simultaneously blocks flow of air through the line 69. The effect of this may be readily seen by reference to Fig. 3. Exhausting the chamber 71 causes the diaphragm 70 to move all the way to the right under the influence of the spring 42. This closes the valve 82 and opens the valve 75, so that the full pressure of the air in the reservoir 35 is applied to the brake cylinder 21. This causes the belt 20 to slow down the roll 12 in a minimum amount of time.

In spite of the rapid braking of the roll 12, the degree of braking force is precisely controlled so that tearing of the web is substantially eliminated. This is accomplished by an appropriate adjustment of the pressure regulator 31. It will be apparent, therefore, that the regulator 31 performs two functions. In the first place, it insures precise pressure regulation of high pressure air which is supplied to the pressure regulator 40 and to the regulator valve 60. In addition, it insures that the braking force on the paper roll matches the braking force applied to the press by the normal press drive mechanism so that the press and paper roll stop in unison with one another and with reasonable web tension. The adjustment of the regulator to accomplish the latter function is well within the skill of the art.

For the purpose of slacking off the belt 20, a 3-way shut-off valve 100 is placed in the line 43.

Rsum of operation While the operation of the device will be apparent from the foregoing, it may be helpful to summarize it briefly:

Prior to starting up the press, the pressure regulator 60 may be set to the point of desired web tension. This tension is maintained by the control arrangement during acceleration and after the press comes up to speed. In the event that tension in the web momentarily drops below the desired value, the balance of forces at the floating roller is upset and the roller tends to swing bodily to the right under the urging of the loading cylinder 55. This results in inward movement of the control rod 41, which changes the setting of the variable pressure regulator 40. The latter produces a slightly higher output pressure, which is applied both to the brake cylinder 21 and to the compensating cylinder 80. The increase in the force exerted by the compensating cylinder exactly overcomes the opposing force of the spring 42 so that the floating roller is perfectly free to move. The increased pressure at the brake cylinder causes a correspondingly increased braking force on the roll 12. The resulting increase in web tension causes the floating roller to move leftward to its initial equilibrium position. The converse sequence of events occurs when the tension in the web increases above the set value for any reason.

When slowdown is initiated by the press speed controller 92, the roll 12, because of its momentum, tends to continue rotation at its initial speed. This tends to remove tension momentarily from the web, and the floating roller is therefore free to move to the right (Fig. 1) under the influence of the loading cylinder 55. However, because of the constriction at the input of the loading cylinder, there is a slight time delay. The effect of such delay is, however, completely overcome by closure of the contacts 96 (Fig. 6), which causes immediate movement of the auxiliary spring to the active position. This urges the floating roller toward the right independently of movement of the plunger in the loading cylinder. Such movement, acting upon the variable pressure regulator, causes immediate flow of air into the belt actuator and an immediate increase in braking pressure, thereby absorbing the excess energy stored in the roll and insuring against temporary loss of tension in the web. After the floating roller has been moved to the right-hand portion of its range by the spring 90, the function :of the spring is completed even though it may notreturn immediately to its inactive position, and the floating roller continues its automatic control of web tension.

When it is necessary to press thered button 99 in an emergency to stop the press, closure .of the contacts actuates the valve 67 to disable the variablepressure regulator 40 and to apply air from the line 34 directly to the belt actuator 21. The amount of braking under such conditions is limited by the adjustment of the regulator 31 to a point below' that which will cause breakage of the web.

Since the system is substantially closed, loss of pressure fluid air in the present instance is 'kept'to a minimum. Furthermore, due to the fine degree of control the traverse of the control element and the brake cylinder is minimized. For these and other reasons which will be apparent to one skilled in-the art, the energy requirements of the arrangement are lower than in more conventional tension control systems.

Because of the simplicity of the arrangement, adjustment and maintenance are both kept to a minimum. The only adjustment required on the part of the press-operator is the setting of the regulator 60 directly in terms of desired web tension.

This application is a continuation-'in-part of copending application Serial No. 304,405, filed August 14, 1952.

I claim as my invention:

1. In a tension control system for maintaining a desired tension in a running Web fed from a paper roll, the combination comprising a brake belt peripherally engaging the roll to apply a braking force thereto, a pressure fluid actuator connected to said belt for tensioning the latter, a variable pressure regulator having a'spring-returned control element and having a connection with a source of pressure fluid for applying fluid to said actuator at a pressure corresponding to the position of the control element, means responsive to the output pressure of the regulator for neutralizing the force of the spring, a floating roller for engaging a loop in the running web, means including a source of adjustable bias for mounting said roller for bodily movement in response to changes in loop tension, means for coupling the control element of 1obination comprising a brake belt peripherally engaging the roll to apply a braking force thereto, a pressure fluid actuator connected to said belt for tensioning the latter, a variable pressure regulator having a control element and having a connection with a source of pressure fluid for applying fluid to said actuator at a pressure corresponding to the position of the control element, a floating roller for engaging a loop in the running web, means including a source of adjustable bia' for mounting said roller for bodily movement in respons to changes in loop tension, means for coupling the control element of the regulator to said roller so that a change in tension in the loop from an equilibrium value causes a corrective change in braking force, and stops for limiting the range of movement of the floating roller to about one-quarter of an inch.

4. In a tension control system for maintaining a desired tension in a running web fed from a paper roll, the combination comprising a brake belt peripherally engaging the roll. to apply a braking force thereto, a pressure fluid actuator coupled to the high tension end of 'said beltfor tensioning the latter, a first variable pressure the regulator to said roller'so' that a departure in the tension in the loop from its adjusted equilibrium value causes'a corrective change in braking force, said regulator being so' constructed and arranged that less than about one-quarter of an inch of roller movement is effective to increase the braking force'from substantially zero to a safe maximum value, and stops for'limiting the movement of the floating roller substantially to such .range.

2. In a tension control system for maintaining a desired tension in a running web fed from a paper roll, the combination comprising a brake belt peripherally engaging the roll to apply a braking force thereto, a pressure fluid actuator connected to said belt for tensioning the latter, a pressure regulator having a control element and having a connection with a source of pressure fluid for applying fluid to said actuator at a pressure corresponding to the position of the control element, a floating roller for engaging a loop in the running web,'means including a source of adjustable bias for mounting said roller for bodily movement in response to changes in loop tension, means for coupling the control element of the regulator to said roller so that a change in tension in the loop from an equilibrium value causes a corrective change in braking force, said regulator and actuator being, so constructed and arranged so that the braking force is varied between maximum useful limit conditions by movement of the floating roller within a range having a Width whichis not less than one-tenth inch nor greater than one inch, and stops for limiting the movement of the floating roller to such range.

tension in a running web fed from a paper roll, the comregulator having a control element and having a connection with a source of pressure fluid for applying fluid to'. said actuator at a pressure corresponding to the position of the control element, a floating roller for engaging a loop in the running Web, means for mounting said roller for bodily movement in response to changes in'loop tension, a loading cylinder for biasing said roller mounting means in a direction to elongate the loop a second variable pressure regulator having a manual adjustment for adjusting the pressure in the loading cylinder, and means for coupling the control element of the first regulator to said roller so that a change in tension in the loop from the equilibrium value determined by said loading cylinder causes a corrective change in braking force.

5. In a tension control system for maintaining a desired tension in a running web fed from a paper roll, the combination comprising a brake belt peripherally engaging, the roll to apply a braking force thereto, a pressure fluid actuator coupled tov the high tension and of said belt for tensioning the latter, a source of pressure fluid at constant pressure, a variable pressure regulator having a control element and having a connection with said constant pressure source of pressure fluid for applying fluid to said actuator at a pressure corresponding to the position of the control element, a floating roller for engaging aloop in the running web, biased means for mounting said roller for bodily movement in response'to changes in loop tension, means for coupling the control element of the regulator to said roller so that a change in tension in the loop from an equilibrium value causes a corrective change in braking force, and means including a red button stop control for disabling said regulator and for connecting the actuator for direct supply from said constant pressure source.

6. In a tension system for maintaining adesired tension in a running web fed from a paper roll, the combination comprising a brake belt peripherally engaging the roll to apply a braking force thereto, a pressure fluid actuator coupled to the high tension endof said belt for tensioning the latter, a source of pressure fluid having a constant pressure regulator, a variable pressure regulator fed from said constant pressure regulator, said variable pressure regulator having a movable control element and arranged to ment, a floating roller for engaging a loop in the running web, biased means for mounting said roller for bodily movement in response to changes in loop tension, means for coupling the control element of the variable pressure regulator to said roller so that a change in tension in the loop from an equilibrium value causes a corrective change in braking force, means including a red button stop" control for disabling said variable pressure regulator and for connecting the actuator directly to the output of said constant pressure regulator, and means on said constant pressure regulator for adjusting the output pressure thereof to a value below that which will cause breakageof the web.

,7. In a tension control system for a printing press for maintaining a desired tension in a running web fed from a paper roll, the combination comprising a brake belt peripherally engaging the roll to apply a braking force thereto, a pressure fluid actuator connected to said belt for tensioning the latter, a regulator having a control element and having a connection with a source of pressure fluid for applying fluid to said actuator at a pressure corresponding to the position of the control element, a floating roller for engaging a loop in the running web, means for mounting said roller for bodily movement in response to changes in loop tension, a loading cylinder having an adjustable source of fluid pressure for biasing said roller mounting means in the loop elongating direction, means for coupling the control element of the regulator to said roller so that a change in tension in the loop from an equilibrium value causes a corrective change in braking force, and means arranged to be actuated during slowdown of the printing press for applying additional bias to said roller mounting means.

8. In a tension control system for maintaining a desired tension in a running web fed from a paper roll, the combination comprising a brake belt peripherally engaging the roll to apply a braking force thereto, a pressure fluid actuator connected to said belt for tensioning the latter, a variable pressure regulator having a control element and having a connection with a source of pressure fluid for applying fluid to said actuator at a pressure corresponding to the position of the control element, a floating roller for engaging a loop in the running web, means for mounting said roller for bodily movement in response to changes in loop tension, a loading cylinder having a manually adjustable source of pressure fluid for biasing said roller mounting means in a direction to elongate the loop, and means for coupling the control element of the regulator to said roller so that a change in tension in the loop from the equilibrium value determined by said loading cylinder causes a corrective change in braking force, said loading cylinder having a constriction at its input to impede the free flow of fluid and thereby provide a limited amount of shock-absorbing action for said floating roller.

9. In a tension control system for a printing press for maintaining a desired tension in a running web fed from a paper roll, the combination comprising a brake belt peripherally engaging the roll to apply braking force thereto, a pressure fluid actuator connected to said belt for tensioning the latter, a variable pressure regulator having a movable control element and having a connection with a source of pressure fluid for applying fluid to said actuator at a pressure corresponding to the position of the control element, a floating roller for engaging a loop in the running web, means for mounting said roller for limited bodily movement between a short loop position and a long loop position in response to changes in loop tension, a loading cylinder having an adjustable source of fluid pressure for biasing said roller mounting means in the loop-elongating direction, means for coupling the control element of the regulator to said roller so that a change in tension in the loop from an equilibrium value causes a corrective change in braking force, said loading cylinder having damping means connected thereto to damp its movement in response to applied fluid pressure, and means arranged to be actuated upon initiating slowdown of the printing press for forcibly moving said floating roller out of its short loop position independently of movement of said loading cylinder.

10. In a tension control system for a printing press for maintaining a desired tension in a running web feed from a paper roll, the combination comprising a brake belt peripherally engaging the roll to apply braking force thereto, a pressure fluid actuator connected to said belt for tensioning the latter, a variable pressure regulator having a movable control element and having a connection with a source of pressure fluid for applying fluid to said actuator at a pressure corresponding to the position of the control element, a floating roller for engaging a loop in the running web, means for mounting said roller for bodily movement in response to changes in loop tension, a loading cylinder having an adjustable source of fluid pressure for biasing said roller mounting means in the loop-elongating direction, means for coupling the control element of the regulator to said roller so that a change in tension in the loop from an equilibrium value causes a corrective change in braking force, said loading cylinder having a damping element connected thereto to impede the free flow of fluid to and from the loading cylinder, and means arranged to be actuated upon initiating slowdown of the printing press for applying pressure fluid to said actuator independently of the movement of said loading cylinder.

11. In a tension control system for a printing press for maintaining a desired tension in a running web fed from a paper roll, the combination comprising a brake belt peripherally engaging the roll to apply braking force thereto, a pressure fluid actuator connected to said belt for tensioning the latter, a variable pressure regulator having a movable control element and having a connection with a source of pressure fluid for applying fluid to said actuator at a pressure corresponding to the position of the controlelement, a floating roller for engaging a loop in the running web, means for mounting said roller for bodily movement in response to changes in loop tension, a loading cylinder having an adjustable source of fluid pressure for biasing said roller mounting means in the loop-elongating direction, means for coupling the control element of the regulator to said roller so that a change in tension in the loop from an equilibrium value causes a corrective change in braking force, said loading cylinder having a two-way shock-absorber connected thereto to damp themovement thereof, and means arranged to be actuated upon initiating slowdown of the printing press for forcibly, moving said floating roller in a direction to elongate the loop.

12. In a tension control system for a printing press for maintaining a desired tension in a running web fed from a paper roll, the combination comprising a brake belt peripherally engaging the roll to apply braking force thereto, a pressure fluid actuator connected to said belt for tensioning the latter, a variable pressure regulator having a movable control element and having a connection with a source of pressure fluid for applying fluid to said actuator at a pressure corresponding to the position of the control element, a floating roller for engaging a loop in the running web, means for mounting said roller for bodily movement in response to changes in loop tension, 2. loading cylinder having an adjustable source of fluid pressure for biasing said roller mounting means in the loop-elongating direction, means for coupling the control element of the regulator to said roller so that a change intension in the loop from an equilibrium value causes a corrective change in the braking force, said loading cylinder having a constriction at its input to impede thefree flow of fluid to and from the loading cylinder, and means arranged to be actuated upon initiating slowdown of the printing press for forcibly moving saidI floating roller in a direction to elongate the loop.

13. In a tension control system for a printing press for maintaining a desired tension in a running web fed from a paper roll, the combination comprising a brake belt peripherally engaging the roll to apply braking force thereto, a pressure fluid actuator connected to said belt for tensioning the latter, a variable pressure regulator having a movable control element and having a connection with a source of pressure fluid for applying fluid to said actuator at apressure corresponding to the position 13 a of the control element, a floating roller for engaging a loop in the running web, means for mounting said roller for bodily movement in response to changes in loop tension, a loading cylinder having an adjustable source of fluid pressure for biasing said roller mounting means in the loop-elongating direction, meansfor coupling the control element of the regulator to said roller so that *a change in tension in the loop from an equilibrium ing slowdown of the printing press for moving said spring into its active position to cause movement of the floating roller in the loop-elongating direction independently of any delay in the movement of said loading cylinder.

14. In a tension control system for maintaining a desired tension in a running web fed from a paper roll, the combination comprising a stationary belt peripherally engaging the roll to apply a braking force thereto and having a low tension end and a high tension end, a pressurerfluid actuator connected to saidbelt'fortensioning the latter, a variable pressure regulator having a control element and having a connection with a source of pressure fluid for applying fluid to said actuator at a pressure corresponding to the position of the control-element, a floating roller for engaging a loop in the running web, means for mounting said roller for bodily movement in response to changes in loop tension and biased in a direction to elongate the loop, means for coupling the control element of the regulator to said roller so that a change in tension in the loop causes a corrective change in braking force, said actuator being connected to the high tension end of the belt and having an associated spring for cushioning the braking force.

15. In a tension control system for maintaining a desired tension in a running web fed from a paper roll, the combination comprising a brake belt peripherally engaging the roll to apply a braking force thereto, a pressure fluid actuator connected to said belt for tensioning the latter, a variable pressure fluid regulator having a control element and having a connection with a source of pressure fluid for applying fluid to said actuator at a pressure corresponding to the position of the control element, a floating roller for engaging a loop in the running web, means including a pendulous hanger for mounting said roller for bodily movement in response to changes in loop tension, means including a loading cylinder having an adjustable source of fluid pressure for biasing the hanger in a direction to elongate the loop, means for coupling the control element of the regulator to said roller so that a change in tension in the loop from that corresponding to the setting of the loading cylinder causes a corrective change in braking force.

16. In a tension control system for maintaining a desired tension in a running web fed from a paper roll, the combination comprising a brake belt peripherally engaging the roll to apply a braking force thereto, a pneumatic actuator connected to said belt for tensioning the same, a variable pneumatic pressure regulator having a control rod and a control spring therefor and in which the output pressure is a direct function of the force applied to the control rod, means for connecting the pneumatic actuator to the output of said regulator, a floating roller for engaging a loop in the running web, means for mounting said roller for bodily movement and having means for biasing the roller in a direction to increase the size of the loop, means for coupling the control rod of the regulator to said roller so that a change in tension in the loop from an equilibrium value causes a corrective change in braking force, and means for counterbalancing the control spring in all positions of the control rod.

17. In a tension control system for maintaining a desired tension in a running web fed from a paper roll, the combination comprising a brake belt peripherally engaging the roll'to apply a braking force thereto, a pneumatic actuator connected to said belt for tensioning the same, a variable pneumatic pressure regulator having a control rod and a control spring therefor and .in which the output pressure is a direct function of the force applied to the control rod, means for connecting the pneumatic actuator to the output of said regulator, a floating roller for engaging a loop in the running web, meansfor mounting said roller for bodily movement and having means for biasing the roller in a direction to increase the size of the loop, a compensating cylinder connected to the output of said regulator for applying pressure to the control rod which is substantially equal and opposite to the force exerted by the control spring, and means for coupling the control rod of the regulator to said roller so that a change in tension in the loop causes a corrective change in braking force.

18. ha tension control system for maintaining a' desired tension in a running web fed from a paper roll, the combination comprising a brake belt peripherally engaging the roll to apply a braking force thereto, a pneumatic actuator connected to said belt for tensioning the same, a pneumatic pressure regulator having a control rod and in which the output pressure varies in proportion to the displacement of the control rod, means for connecting the pneumatic actuator to the output of said regulator, a floating roller for engaging a loop in the running web, means for mounting said roller for bodily movement, a loading cylinder for biasing the roller mounting in a direction to enlarge the loop, said loading cylinder being filled with oil and having an adjustable source of air pressure in contact with the oil, and means for coupling the control rod of the regulator to said roller so that a change in tension in the loop from the equilibrium position determined by said loading cylinder causes a corrective change in braking force.

19. In a tension control system for maintaining a desired tension in a running web fed from a paper roll, the combination comprising a brake belt peripherally engaging the roll to apply a braking force thereto, a pressure fluid actuator connected to said belt for tensioning the latter, a variable pressure device having a control element and having a connection with a source of pressure fluid forapplying fluid to said actuator at a pressure corresponding to the position of the control element, a floating roller for engaging a loop in the running web, means including a loading cylinder for mounting said roller for bodily movement in response to changes in loop tension, means for coupling the control element of the pressure device to said roller so that a departure in the tension in the loop from its adjusted equilibrium value causes a corrective change in braking force, said pressure device being so constructed and arranged that movement of the floating roller over a range of at least one-tenth of an inch but not more than a range of about one inch is effective to increase the braking force from substantially zero to a safe maximum value, and stops for limiting the movement of the floating roller substantially to such range.

20. In a tension control system for maintaining a desired tension in a running web fed from a paper roll, the combination comprising a brake belt peripherally engaging the roll to apply a braking force thereto, a pressure fluid actuator connected to said belt for tensioning the latter, a variable pressure device having a control element and having a connection with a source of pressure fluid for applying fluid to said actuator at a pressure corresponding to the position of the control element, a floating roller for engaging a loop in the running web, means including a source of adjustable bias for mounting said roller for bodily movement in response to changes in loop tension, means for coupling the control element of the pressure device to said roller so that a departure in the tension in the loop from its adjusted equilibrium value causes a corrective change in braking force, said pressure device being so constructed and arranged that less than about one inch of roller movement is effective to increase the braking force from substantially zero to a safe maximum value, stops for limiting the movement of the floating roller substantially to such range, and twoway shock absorber means coupled to the floating roller, said shockabsorbing means being 50 adjusted as to enable the floating roller to yield to changes in tension resulting from unrolling the web from a low spot on an out-of-round roll without exceeding the breaking stress of the web.

21. In a tension control system for a printing press for maintaining a desired tension in a running web fed from a paper roll, the combination comprising a belt peripherally engaging the roll to apply a braking force thereto, a pressure fluid actuator connected to said belt for tensioning the latter, a variable pressure device having a control element and having a connection with a source of pressure fluid for applying fluid to said actuator at a pressure corresponding to the position of the control element, a floating roller for engaging a loop in the running web, means for mounting said roller for bodily movement in response to changes in loop tension, a loading cylinder having an adjustable source of fluid pressure for biasing said roller mounting means in the loop-elongating direction, means for coupling the control element of the pressure device to said roller so that a change in tension in the loop from an equilibrium value causes a corrective change in braking force, and means arranged to be actuated during slow down of the printing press for moving the roller mounting means into the portion of its range of movement corresponding to increased braking pressure but leaving said roller free for movement in such portion of. its range.

22. In a tension control system for maintaining a desired tension in a running Web fed from a paper roll, the combination comprising a brake belt peripherally engaging the roll to apply a braking force thereto, a pressure fluid actuator coupled to one end of said belt for tensioning the latter, a variable pressure device having a control element and having a connection with a source of pressure fluid for applying fluid to said actuator at a pressure corresponding to the position of the control element, a floating roller for engaging a loop in the running web, means for mounting said roller for bodily movement in response to changes in loop tension, a loading cylinder for applying an adjustable biasing force to said roller mounting, means for coupling the control element of the pressure device to said roller so that a change in tension in the loop from an equilibrium value causes a corrective change in braking force, and a twoway shock absorber coupled to said loading cylinder for providing controlled yielding movement of the latter in response to transient changes in tension.

References Cited in the file of this patent UNITED STATES PATENTS 

